Ribonucleotides can form through selective prebiotic pathways.
The phosphate linkage is far from the easiest ionic linkage that could have evolved on the early Earth.
RNA’s components can be selectively “picked” from the pool of possible prebiotic monomers
Noncanonical nucleic acids could have formed more easily than canonical nucleic acids on the early Earth.
RNA would have been the preferred molecule for polymerization when compared to potential alternatives.
Noncanonical nucleosides provide a more favorable scaffold for oligomerization than canonical nucleosides.
It would have been too difficult to transition from an RNA-only world to the RNA-DNA world life uses today.
RNA could have been a fully sufficient molecule on the early Earth, with both catalytic and informational functions.
RNA’s base pairing abilities are perfect for the initial genetic polymer and needed no other precedent.